We report the molecular beam epitaxy growth of a new laser structure on n-type (1 0 0) InAs substrate, which was designed fur emission near 3 mum at 80K and 3.3 mum at room temperature. This structure employs the InAsSb/InAs/InAsSb/InAlAsSb type-II "W" configuration in the active region, broad InAlAsSb waveguides, and AlAsSb cladding layers. Lattice-matching of In0.88Al0.12As1-xSbx quaternary alloy was obtained at a low temperature (420 degreesC) by controlling the Sb-2/(Sb-2 + As-2) BEP ratio using high V/III flux ratios, while the growth of AlAs0.16Sb0.84 was performed at higher temperatures (480 degreesC and 525 degreesC) using a quasi stoichiometric growth method, based on the control of Al, As and Sb incorporation rates with a V/III ratio close to one. Laser diodes fabricated from these structures showed laser emission near 1.95 mum at 80 R with a threshold current density of 150 A/cm(2). The devices operated in pulsed mode up to 155 K. Ridge lasers exhibited continuous wave operation at 80 E: with an optical power efficiency of 62.5 mW/A/facet.